3SUY

Crystal structure of THF riboswitch, unbound status


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 3.21 Å
  • R-Value Free: 0.269 
  • R-Value Work: 0.223 

wwPDB Validation 3D Report Full Report


This is version 1.1 of the entry. See complete history

Literature

Long-range pseudoknot interactions dictate the regulatory response in the tetrahydrofolate riboswitch.

Huang, L.Ishibe-Murakami, S.Patel, D.J.Serganov, A.

(2011) Proc.Natl.Acad.Sci.USA 108: 14801-14806

  • DOI: 10.1073/pnas.1111701108
  • Primary Citation of Related Structures:  3SUH, 3SUX

  • PubMed Abstract: 
  • Tetrahydrofolate (THF), a biologically active form of the vitamin folate (B(9)), is an essential cofactor in one-carbon transfer reactions. In bacteria, expression of folate-related genes is controlled by feedback modulation in response to specific b ...

    Tetrahydrofolate (THF), a biologically active form of the vitamin folate (B(9)), is an essential cofactor in one-carbon transfer reactions. In bacteria, expression of folate-related genes is controlled by feedback modulation in response to specific binding of THF and related compounds to a riboswitch. Here, we present the X-ray structures of the THF-sensing domain from the Eubacterium siraeum riboswitch in the ligand-bound and unbound states. The structure reveals an "inverted" three-way junctional architecture, most unusual for riboswitches, with the junction located far from the regulatory helix P1 and not directly participating in helix P1 formation. Instead, the three-way junction, stabilized by binding to the ligand, aligns the riboswitch stems for long-range tertiary pseudoknot interactions that contribute to the organization of helix P1 and therefore stipulate the regulatory response of the riboswitch. The pterin moiety of the ligand docks in a semiopen pocket adjacent to the junction, where it forms specific hydrogen bonds with two moderately conserved pyrimidines. The aminobenzoate moiety stacks on a guanine base, whereas the glutamate moiety does not appear to make strong interactions with the RNA. In contrast to other riboswitches, these findings demonstrate that the THF riboswitch uses a limited number of available determinants for ligand recognition. Given that modern antibiotics target folate metabolism, the THF riboswitch structure provides insights on mechanistic aspects of riboswitch function and may help in manipulating THF levels in pathogenic bacteria.


    Organizational Affiliation

    Structural Biology Program, Memorial Sloan-Kettering Cancer Center, 1275 York Avenue, New York, NY 10065, USA. huanglilisioc@hotmail.com




Macromolecules

Find similar proteins by: Sequence  |  Structure

Entity ID: 1
MoleculeChainsLengthOrganism
riboswitchX101[Eubacterium] siraeum V10Sc8a
Small Molecules
Modified Residues  1 Unique
IDChainsTypeFormula2D DiagramParent
CCC
Query on CCC
X
RNA LINKINGC9 H13 N3 O10 P2C
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 3.21 Å
  • R-Value Free: 0.269 
  • R-Value Work: 0.223 
  • Space Group: H 3 2
Unit Cell:
Length (Å)Angle (°)
a = 124.172α = 90.00
b = 124.172β = 90.00
c = 150.428γ = 120.00
Software Package:
Software NamePurpose
REFMACrefinement
REFMACphasing
CBASSdata collection
HKL-2000data reduction
HKL-2000data scaling

Structure Validation

View Full Validation Report or Ramachandran Plots



Entry History 

Deposition Data

Revision History 

  • Version 1.0: 2011-09-14
    Type: Initial release
  • Version 1.1: 2012-03-14
    Type: Database references